Orbital hand tool apparatus for drilling

ABSTRACT

A hand tool apparatus uses a cutting tool with a first width and a tool axis to machine a hole in an object. The hole has a second width at least as large as the first width of the cutting tool. The apparatus includes a housing, a spindle unit in the housing for rotating the cutting tool and an orbital drive for rotating the spindle unit. An axial feed mechanism moves the orbital drive and the spindle unit jointly either toward or away from the object being machined.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation-in-part of U.S. patent application Ser.No. 09/388,419, entitled “HAND TOOL APPARATUS FOR ORBITAL DRILLING”,filed Sep. 1, 1999.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a hand tool for cutting a holein an object, and, more particularly, a hand tool for cutting a holethat has a larger diameter than the diameter of the cutting tool.

[0004] 2. Description of the Related Art

[0005] U.S. Pat. No. 5,641,252 discloses a method for machining holes ina fiber reinforced composite material by using at least one cutting toolwith wear resistant surface positioned eccentrically in relation to acentral axis. The material is machined simultaneously in both an axialand a radial direction by causing the tool to move axially whilerotating not only about its own axis, but also eccentrically about thecentral axis. In accordance with one particular characterizing featureof the invention, the workpiece is oriented in such a way that the axisof rotation of the tool is essentially orthogonal in relation to thelongitudinal directions of the fibers in the immediate vicinity of thepoint where the tool meets the working surface. The diameter of thecutting tool is substantially smaller than the diameter of the hole thatis produced. The eccentric rotary motion is generally a strictly rotarymotion, i.e., it is executed with a constant distance between thecentral axis and the axis of rotation of the cutting tool. This distancebetween the central axis and the axis of rotation of the cutting toolcan be increased by linear increments as the eccentric rotary motioncontinues.

[0006] This known method has a number of substantial advantages ascompared with generally familiar techniques. For example, the methodpermits the production of holes without strength reducing damage. Also,the method permits the production of holes free from damage withouthaving to preform a hole. Further, the method permits the production ofholes to tight tolerances. The dimensional accuracy of the hole isdetermined substantially by the accuracy of the positioning of the toolrelative to the central axis. The requirements imposed on the geometryof the cutting tool are not particularly high, on the other hand, sinceevery individual tool is simply calibrated before use. Additionally, themethod prevents the tool from becoming blocked. Since the diameter ofthe tool is substantially smaller than that of the hole, the methodpermits material removed by cutting to be carried away by simple means,such as with compressed air. The method also permits effective coolingof the tool and the edge of the hole. Yet another advantage is that themethod substantially reduces the cost of wear compared to previouslydisclosed methods, due to the tool being coated with a wear resistantmaterial, such as diamond coating. Moreover, this method also offersadvantages when machining other materials such as metals.

[0007] U.S. patent application Ser. No. 09/092,467 discloses a spindleunit that includes a spindle motor that is rotatable about a principalaxis. The spindle motor includes a tool holder having a tool axissubstantially parallel to the principal axis. The tool holder isrotatable about the tool axis. An axial actuator is configured formoving the spindle motor in an axial feed direction substantiallyparallel to each of the principal axis and the tool axis. A radialactuator adjusts a radial distance between the principal axis and thetool axis. This spindle unit can be mounted in a stationary machine suchas a CNC machine, robot or a simple rig.

[0008] PCT application PCT/SE94/00085 discloses a hand tool machine formachining holes according to the above described technique. Thisdisclosure relates to a hand machine for making holes in an object madeof composite fibers, preferably with a curved surface. The center axisof the hole passes through a predetermined point on the surface of theobject and is oriented in a certain direction relative to thelongitudinal direction of the fibers of the object which are close tothe point. The machine includes, in combination, a tool holder rotatingabout its own axis and a principal axis, a device for adjusting the axisof rotation of the tool holder in the normal direction of the surface atthe point, a device for axial feeding of the tool holder relative to theobject, a device for adjusting the radial distance between the principalaxis and the axis of rotation of the tool holder, and a device fortaking up the forces and moments between the machine and the object thatresult from the making of the holes.

[0009] Although this aforementioned disclosure outlines some principles,the disclosed hand tool does not offer a feasible and practicalsolution. One obvious limitation is that the disclosed concepts do notpresent a solution for title power supply and therefore their potentialfor realization must be questioned. One basic requirement for a handtool is light-weight and user friendliness. The disclosed concepts donot provide a compact integrated light-weight design. Furthermore, theillustrated concepts show solutions which require a very long tooloverhang, which is a severe limitation due to the radial cutting force,which creates a bending moment on the cutting tool.

[0010] When machining holes according to the proposed method, i.e., bypositioning, the tool eccentrically in relation to a central axis andmachining simultaneously in both an axial and radial direction bycausing the tool to move axially and to rotate not only about its ownaxis, but also eccentrically about a central axis, the tip of the toolis subjected to both an axial force and a radial force. The radial forcecreates bending moment on the tool, the magnitude of which is dependenton both the magnitude of the force and on the length of the tooloverhang (moment arm). It is desirable to minimize the bending momentfor optimal machining accuracy. This can be achieved by minimizing thetool overhang, i.e., the free length of the tool. The conceptsillustrated in PCT/SE94/00085 show situations where the tool overhang isdetermined by the thickness of the hole template and by the thickness ofthe workpiece. Since the thickness of the template may be substantial,the tool overhang may be accordingly substantial.

SUMMARY OF THE INVENTION

[0011] The present invention provides a rotary hand tool apparatus usinga cutting tool to machine a hole in an object such that the hole has awidth at least as large as the width of the cutting tool. The centerlineof the hole passes through a predetermined point on the surface of theobject. Moreover, the present invention provides a compact andlightweight hand tool apparatus for machining holes in a flat or curvedobject of any material by rotating a cutting tool about its own axis andabout a principal axis while simultaneously feeding in the axialdirection. A lightweight and compact apparatus is achieved byintegrating a radial offset mechanism spindle motor and orbital drive ina same actuating assembly package, which rotates about a principal axisand is jointly advanced and with-drawn by the axial feed mechanism.

[0012] The invention comprises, in one form thereof, a hand toolapparatus for using a cutting tool with a first width and a tool axis tomachine a hole in an object, the hole having a second width at least aslarge as the first width of the cutting tool. The apparatus has ahousing including a top and a bottom plate and a carrier axiallymoveable between the top and the bottom plate. A spindle unit having aprincipal axis includes a spindle motor and a spindle shaft for drivingthe tool. The spindle unit extends through the carrier and is securedthereto against axial movement while being rotational relative to thecarrier about the principle axis. An orbital drive motor is mounted onthe carrier, and is drivingly connected to the spindle unit for rotatingthe spindle unit about the principal axis relative to the carrier. Anaxial feed mechanism is configured for moving the carrier between thetop and the bottom plate.

[0013] In another form thereof, the invention provides an axial feedmechanism for a hand tool, the hand tool having a principal axis, ahousing including a top and a bottom plate, a spindle unit rotatable inthe housing about the principal axis, and a motor configured forrotating the spindle unit about the principal axis. The axial feedmechanism has a carrier moveable along the principal axis between thetop and the bottom plate. The carrier is secured to the spindle unit inan axial direction, and the spindle unit is rotatable in the carrierabout the principal axis. The motor is secured to the carrier; and anaxial adjustment cylinder is secured to the housing. A cylinder rod isextendable and retractable relative thereto, and the cylinder rod issecured to the carrier.

[0014] In still another form thereof, the invention provides a hand toolapparatus for using a cutting tool to machine a hole in an object. Thehand tool apparatus has a housing, a spindle unit disposed in thehousing and configured for rotating the cutting tool, and an orbitaldrive disposed in the housing and configured for rotating the spindleunit. An axial feed mechanism is associated with the housing andconfigured for advancing and withdrawing the spindle unit and theorbital drive jointly within the housing relative to the object.

[0015] An advantage of the present invention is that the hand tool ismore lightweight and compact than the previous devices.

[0016] Another advantage is that the tool overhand is minimized, therebyreducing the bending moment on the cutting tool.

[0017] Yet another advantage is that the tool can be mounted into thetool holder from the rear, thereby allowing the tool holder to have aconical shape which minimizes the required diameter of the holes in thetemplate.

[0018] Still another advantage is that side-by side positionalrelationships are present between major components, reducing overalltool length and deflection between components.

[0019] A still further advantage is that the drive connections betweenthe spindle unit and the cutting tool, and between the orbital drive andthe spindle unit are substantially fixed, with the combined assemblyadvanced and retracted by the axial feed mechanism, thereby stabilizingthe drive relationships for any position of the cutting through out thelinear path traveled by the cutting tool.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above-mentioned and other features and advantages of thisinvention, and the manner of attaining them, will become more apparentand the invention will be better understood by reference to thefollowing description of embodiments of the invention taken inconjunction with the accompanying drawings, wherein:

[0021]FIG. 1 is a top, sectional view of one embodiment of a pneumaticportable drill of the present invention;

[0022]FIG. 2 is a top, sectional view of the tool assembly and a portionof the actuating assembly of the pneumatic portable drill of FIG. 1;

[0023]FIG. 3 is a rear, sectional view taken along line 3-3 in FIG. 1,

[0024]FIG. 4A is a side, sectional view of one embodiment of a templateassembly of the portable drill of FIG. 1;

[0025]FIG. 4B is a rear view of the template assembly of FIG. 4A;

[0026]FIG. 5A is a side, sectional view of another embodiment of atemplate assembly of the pneumatic portable drill of FIG. 1;

[0027]FIG. 5B is a rear view of the template assembly of FIG. 5A;

[0028]FIG. 6 is a side view of the pneumatic portable drill of FIG. 1;

[0029]FIG. 7 is a rear view of the pneumatic portable drill of FIG. 1;

[0030]FIG. 8A is a schematic, sectional view, taken along line 3-3 ofFIG. 1, of the relative positions of the tool, inner sleeve and outersleeve;

[0031]FIG. 8B is a view similar to FIG. 8A, with the inner sleeverotated 90E counterclockwise relative to its position in FIG. 8A;

[0032]FIG. 5C is a view similar to FIG. 8A, with the inner sleeverotated 180E counterclockwise relative to its position in FIG. 8A;

[0033]FIG. 9 is a perspective view of a second embodiment of theinvention;

[0034]FIG. 10 is an elevational view of the embodiment shown in FIG. 9;

[0035]FIG. 11 is an elevational view similar to FIG. 10, butillustrating a different functional position; and

[0036]FIG. 12 is a cross-sectional view of the embodiment as shown inFIG. 11. Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrates one preferred embodiment of the invention, in one form, andsuch exemplifications are not to be construed as limiting the scope ofthe invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

[0037] Referring now to the drawings, and particularly to FIG. 1, thereis shown a hand tool apparatus in the form of a pneumatic portable drill10. Drill 10 includes an actuating assembly 12, eccentric rotationmechanism 14, tool assembly 16, template assembly 18, axial positioningmechanism 20 (FIG. 6), stroke adjustment mechanism 22 and an axial feedmechanism 24.

[0038] Actuating assembly 12 includes a spindle motor 26, and a radialoffset mechanism 28 (FIG. 3), all contained within a single housing 29.Radial offset mechanism 28 includes a cylindrical inner sleeve 30positioned in a cylindrical outer sleeve 32. Inner sleeve 30 and outersleeve 32 are rotatable relative to each other. An axle or shaft 34 ofspindle motor 26 extends through a clutch 36, and is rotatably mountedin inner sleeve 30.

[0039] Eccentric rotation mechanism 14 includes a motor 38 for rotatingactuating assembly 12, and thereby tool assembly 16, about a principalaxis 40.

[0040] Template assembly 18 includes a sleeve 42 (FIG. 4A) with a flange44 which is in contact with the surface of a work piece 46. A centeraxis 48 of sleeve 42 is oriented substantially perpendicular to thesurface of work piece 46. Sleeve 42 and flange 44 are fastened to atemplate 50 by bolted joints 52. Tool assembly 16 is locked onto sleeve42 by use of a bayonet socket 54, whereby the axes of rotation of drill10 are oriented substantially perpendicular to the surface of work piece46.

[0041] In another embodiment, a sleeve 56 (FIG. 5A) is also oriented inthe hole in template 50 such that axis of rotation 48 of sleeve 56 issubstantially perpendicular to the surface of work piece 46. Sleeve 56can be fixed to template 50 by use of a threaded joint, frictional jointor adhesive joint. Portable drill 10 is then locked onto sleeve 56 byuse of a bayonet socket 54, as shown in FIG. 1, whereby the axes ofrotation are oriented substantially perpendicular to the surface of workpiece 46.

[0042] Tool assembly 16 includes a cutting tool 58, a tool holder 60 anda screw 62. To minimize the tool overhang, template 50 is designed suchthat tool holder 60 can be fed through the holes in template 50. In suchcase, it is desired that tool holder 60 have a small outer diameter,since in many situations it is required to machine multiple holes inwork piece 46, with relatively short spacing distances between theholes. In order to accommodate all holes, the holes in template 50 cannot be made arbitrarily large to make room for tool holder 60.Therefore, it is desirable for tool holder 60 to require as little spaceas possible. This is made possible by tool holder 60 and cutting tool 58being provided with conical surfaces. Cutting tool 58 is mounted in toolholder 60 from the rear end, and tightened in place by screw 62 insidetool holder 60. By this concept, it is possible to obtain a space savingsolution that allows the feeding of tool holder 60 through the holes intemplate 50, without requiring that the template holes be too large.

[0043] Although the aforementioned tool holder concept offers a spacesaving advantage, that allows feeding of tool holder 60 through template50 without requiring very large holes in template 50, the spacingbetween the holes in work piece 46 still may be too small for theembodiment of FIGS. 1 and 5. In such case, drill 10 is locked to analternative fixing device (FIG. 4B) which is fixed in template 50 by twoscrews 52 in two holes located a distance away from the main hole. Thus,the holes in template 50 may be integrated, as in FIG. 4B, which issuitable in a cases where the spacing between the holes in template 50is small.

[0044] Axial positioning mechanism 20 includes a threaded ring 64 and ascale 66. It is desirable to roughly position the tip of cutting tool 58a certain distance from work piece 46, as shown in FIG. 1. This isachieved by threaded ring 64, and is made possible in that housing 29 ofportable drill 10 is separated at ring 64 into a front portion 65 and arear portion 67. By turning ring 64, front portion 65 of drill housing29 moves forward or backward, which movement is indicated by scale 66.

[0045] Stroke adjustment mechanism 22 includes a ring 68 (FIG. 7), a rod70, a lock screw 72, a projection 74, an arm or latch 76 and a returnmechanism 78. The stroke length of the machining operation is adjustedby mechanism 22. Ring 68 is rotatably attached to the drill housing. Onring 68 is fastened a rod 70. Rod 70 is provided with a slot (not shown)such that its axial position is adjustable. The desired position isfixed by lock screw 72. Projection 74, fixedly attached to rod 70,contacts arm 76 of return mechanism 78, and thereby forces drill 10 tomake a return stroke after the contact.

[0046] In operation, axial feed mechanism 24 moves actuating assembly12, and thereby cutting tool 58 in an axial feed direction, and spindlemotor 26 rotates cutting tool 58 about its own axis 80. Motor 38 rotatesactuating assembly 12, and thereby cutting tool 58 about principle axis40.

[0047] An axial feed motion directed towards work piece 46 is providedby supplying compressed air in a circumferential cavity 82. As actuatingassembly 12 moves forward, it forces oil, stored in anothercircumferential cavity 84, to flow through a radial hole 86 via an axialhole 88, another radial hole 90, and hole 92 into space 94 of cylinder96, which contains oil. A piston 98 then moves to the right in FIG. 1 inorder to allow for the volume increase. Thus provided is a hydraulicallydamped axial movement.

[0048] The speed of the axial movement can be controlled by adjustingthe position of a needle 100 in relation to hole 92. An axial feedmotion directed away from work piece 46 (return stroke) is achieved bysupplying compressed air into space 102, which contains air via achannel 104. The pressure increase in cylinder 96 due to the returnstroke causes a valve 106 to open and oil to flow back into cavity 84and thereby create a pressure increase, which causes actuating assembly12 to move away from work piece 46. This design allows for a fasterreturn stroke as compared to the forward feeding movement.

[0049] Air is supplied to spindle motor 26 through openings 108 in thewall element of outer sleeve 32 of actuating assembly 12. The air thenflows in channel 110 to the rear end of spindle motor 26 and thenthrough spindle motor 26 to cause rotation of shaft 34. The return flowis then directed through outlet 112 out to the open air. Outlet 112rotates eccentrically in relation to the center axis of spindle motor26. At the rear end is arranged a sealing 114 and an end piece 116 forreducing the sound level.

[0050] Outer sleeve 32 is turnable or rotatable relative to inner sleeve30, and thereby the axis of rotation 80 of cutting tool 58 and principalaxis 40 can be varied from zero (FIG. 8A) to a maximum value (FIG. 8C)by a relative rotation of 180E between the two sleeves 30, 32. FIG. 8Ashows a case where a 12 millimeter tool 58 is in zero offset position.FIG. 8C shows a case where tool 58 is in its maximum radial offsetposition, i.e., tool 58 is offset two millimeters in order to machine a16 millimeter hole.

[0051] The relative movement between sleeves 30, 32 is achieved byturning a screw 118 (FIG. 3). A stop screw 120 locks sleeves 30 and 32in a desired position. In order to adjust the offset, front portion 65of housing 29 is removed by unlocking a tightening ring 122.

[0052] In order to rotate actuating assembly 12 and thereby cutting tool58 about a principal axis 40, gear wheels 124, 126 transfer the rotationof motor 38 to actuating assembly 12. Since tool holder 60 is connectedto inner sleeve 30 of actuating assembly 12, tool holder 60 and cuttingtool 58 are forced into a rotation about principal axis 40.

[0053] Air is supplied through an opening 128. The speed of motor 38 iscontrolled by adjusting a needle 130 in opening 128. The outlet of theair supplied to motor 38 is not shown.

[0054] An alternate embodiment of the invention is illustrated in FIGS.9-12. Drill 210 includes an actuating assembly in the nature of aspindle unit 212, and an eccentric rotation mechanism in the nature ofan orbital drive unit 214 secured in a housing 216. Housing 216 includesa bottom plate 218, wall 220 and top 222. An axial feed mechanism 224operates on spindle unit 212 and orbital drive unit 214, to adjust theaxial positions thereof in housing 216 between fully advanced and fullyretracted positions, as will be described hereinafter. A tool assembly16, template assembly 18, axial positioning mechanism 20, as describedpreviously, but not shown in FIGS. 9-12, are also used in drill 210.

[0055] Spindle unit 212 includes a spindle motor 226 and a radial offsetmechanism 228 similar to spindle motor 26 and radial offset mechanism 28described previously. Radial offset mechanism 228 includes a cylindricalinner sleeve 230 positioned concentrically in a cylindrical outer sleeve232, which are rotatable relative to each other. A spindle axle 234 isoperatively connected to and driven by spindle motor 226 through aclutch coupling 236. Spindle axle 234 is mounted in inner sleeve 230 byneedle bearings 238 and spindle bearings 240.

[0056] Radial offset is achieved through relative rotational movement oradjustment of inner sleeve 230 and outer sleeve 232 in the same manneras described previously for inner sleeve 30 and outer sleeve 32. Alocking ring 242, axial nut 244 and zero point ring 246 are provided ata front end 246 of spindle unit 212, and a motor cover 248 is providedat a back end 250 of spindle unit 212, secured to inner sleeve 230.

[0057] Spindle unit 212 is mounted in housing 216 by a bushing 260between outer sleeve 232 and bottom plate 218, and a bushing 262 betweenouter sleeve 232 and top 222. A forward guide 264 extending forwardlyfrom bottom plate 218 provides added stability and positioning forspindle unit 212 relative to bottom plate 218. Spindle unit 212 isfurther mounted to a carrier 270 by bearings 272 and 274. Carrier 270 isaxially adjustable in housing 216, as will be described subsequently.

[0058] Orbital drive 214 includes a motor 280 secured in a motor bracket282 on carrier 270. A pulley 284 is mounted on a shaft 286 of motor 280.A drive belt 288 establishes a driving connection between pulley 284 andouter sleeve 232, through a pulley surface (not shown) formed integrallyon outer sleeve 232. Orbit motor 280 thereby rotates spindle unit 212,with carrier 270 held rotationally stationary, together with housing216.

[0059] Axial feed mechanism 224 establishes an axially adjustableinterconnection between housing 216 and carrier 270, and thereby thecomponents carried by carrier 270, including spindle unit 212 andorbital drive 214. An axial adjustment cylinder 300 is mounted on top222 of housing 216, and includes a cylinder rod 302 connected to carrier270. Axial adjustment cylinder 300 is a double acting, fluid operatedcylinder effecting axial movement of carrier 270 both forwardly andbackwardly. A damping cylinder 304 is mounted on carrier 270, andincludes a cylinder rod 306 connected to bottom plate 218, for dampingmovement of carrier 270 in either axial direction.

[0060]FIGS. 9 and 10 show spindle unit 212 in the axial retractedposition. Carrier 270 is near top 222, with cylinder rod 306 retractedwithin axial adjustment cylinder 300. Cylinder rod 306 of dampingcylinder 304 is extended.

[0061] To extend spindle unit 212 forwardly in tool 210, from thepositions illustrated in FIGS. 1 and 2, cylinder rod 302 is extendedfrom axial adjustment cylinder 300 while simultaneously cylinder rod 306is retracted into damping cylinder 304. Carrier 270 is thereby advancedtoward bottom plate 218 and away from top 222. An extended position ofspindle unit 212 is illustrated in FIGS. 11 and 12.

[0062] Since spindle unit 212 and orbital drive 214 are both mounted tocarrier 270, both are axially adjusted together, and the drivingconnection between orbit motor 280 and spindle unit 212 is maintained.Thus, the driving connection between orbit motor 280 and spindle unit212 can be a fixed, stabile connection, not requiring either or both toallow and compensate for movement by the other or both.

[0063] While this invention has been described as having a preferreddesign, the present invention can be farther modified within the spiritand scope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains and which fallwithin the limits of the appended claims.

What is claimed is:
 1. A hand tool apparatus for using a cutting, toolwith a first width and a tool axis to machine a hole in an object, thehole having a second width at least as large as the first width of thecutting tool, said apparatus comprising: a housing including a top and abottom plate; a carrier axially moveable between said top and saidbottom plate; a spindle unit having a principal axis including a spindlemotor and a spindle shaft for driving the tool, said spindle unitextending through said carrier and secured thereto against axialmovement while being rotational relative to said carrier about saidprinciple axis; an orbital drive motor mounted on said carrier, anddrivingly connected to said spindle unit for rotating said spindle unitabout said principal axis relative to said carrier; and an axial feedmechanism configured for moving said carrier between said top and saidbottom plate.
 2. The hand tool apparatus of claim 1, said axial feedmechanism including an axial adjustment cylinder secured to said top andhaving a cylinder rod secured to said carrier.
 3. The hand toolapparatus of claim 2, including a damping cylinder secured to saidcarrier, and having a cylinder rod secured to said bottom plate.
 4. Thehand tool apparatus of claim 1, including a damping cylinder secured tosaid carrier, and having a cylinder rod secured to said bottom plate. 5.The hand tool apparatus of claim 1, said orbital drive motor having amotor shaft and a pulley driven thereby, and a belt drivingly connectingsaid pulley to said spindle unit.
 6. The hand tool apparatus of claim 1,said spindle unit including an inner sleeve and an outer sleeve, saidinner and outer sleeves being rotational relative to each other, saidspindle motor being secured in said inner sleeve and said spindle shaftbeing rotational in said inner sleeve.
 7. The hand tool apparatus ofclaim 6, said outer sleeve being rotational in said top, said carrierand said bottom plate about said principal axis.
 8. The hand toolapparatus of claim 7, said axial feed mechanism including an axialadjustment cylinder secured to said top and having a cylinder rodsecured to said carrier.
 9. The hand tool apparatus of claim 8,including a damping cylinder secured to said carrier, and having acylinder rod secured to said bottom plate.
 10. An axial feed mechanismfor a hand tool, the hand tool having a principal axis, a housingincluding a top and a bottom plate, a spindle unit rotatable in thehousing about the principal axis, and a motor configured for rotatingthe spindle unit about the principal axis, said axial feed mechanismcomprising: a carrier moveable along the principal axis between the topand the bottom plate, said carrier secured to the spindle unit in anaxial direction and the spindle unit rotatable in the carrier about theprincipal axis, and the motor secured to the carrier; and an axialadjustment cylinder secured to the housing, and including a cylinder rodextendable and retractable relative thereto, said cylinder rod securedto said carrier.
 11. The axial feed mechanism of claim 10, said axialadjustment cylinder being secured to the housing top.
 12. The axial feedmechanism of claim 11, including a damping cylinder secured to saidcarrier and having a cylinder rod extendable and retractable relativethereto, said cylinder rod secured to the housing bottom plate.
 13. Theaxial feed mechanism of claim 12, including a belt drivingly connectingthe motor to the spindle unit.
 14. The axial feed mechanism of claim 10,including a belt drivingly connecting the motor to the spindle unit. 15.The axial feed mechanism of claim 10, including a damping cylindersecured to said carrier and having a cylinder rod extendable andretractable relative thereto, said cylinder rod secured to the housing.16. A hand tool apparatus for using a cutting tool to machine a hole inan object, said hand tool apparatus comprising: a housing; a spindleunit disposed in said housing and configured for rotating the cuttingtool; an orbital drive disposed in said housing and configured forrotating said spindle unit; and an axial feed mechanism associated withsaid housing and configured for advancing and withdrawing said spindleunit and said orbital drive jointly within said housing relative to theobject.
 17. The hand tool apparatus of claim 16, said axial feedmechanism including a carrier, said carrier being configured formovement toward and away from the object, and said carrier carrying saidspindle unit and said orbital drive.
 18. The hand tool apparatus ofclaim 17, said axial feed mechanism further including an axialadjustment cylinder for advancing and withdrawing said carrier relativeto the object.
 19. The hand tool apparatus of claim 18, said axial feedmechanism further including a damper cylinder operatively connectedbetween said carrier and said housing.
 20. The hand tool apparatus ofclaim 19, said housing having a bottom plate and a top; said axialadjustment cylinder being secured to and operational between said topand said carrier; and said damper cylinder being secured to andoperational between said carrier and said bottom plate.